Microbicidal system

Abstract

The invention provides a system for sanitizing fluids such as water and air. In particular, the invention provides a combination of solid chlorhexidine and a polymer matrix, for which effluents are essentially free of leached chlorhexidine. The systems enable rapid disinfecting of fluids, including in line at the point of use, and can be employed for both high volume applications and disposable single-use applications.

The invention claimed is: 
     
       1. A microbicidal filtration system comprising:
 a) a set of solid chlorhexidine (CX) particles having the following characteristics:
 i) a purity of at least 97.0% chlorhexidine by weight, when any presence of counterions or water molecules is factored out; and 
 ii) no more than 3.0% by weight of chloroaniline impurities, when any presence of counterions or water molecules is factored out; 
 iii) the CX particles are each characterized in having a releasing surface from which molecular chlorhexidine may dissolve into an aqueous medium that passes over said CX particles or dissolve into a polymer matrix that is juxtaposed at that surface; 
 iv) a particle phase composition selected from the group consisting of amorphous, crystalline, and mixed amorphous and crystalline, wherein the phase composition of each particle is the same as or independent of the phase composition of a majority of other CX particles in the set; 
 
 b) a porous matrix having the following characteristics:
 i) when any presence of chlorhexidine and of chloroaniline impurities is factored out, at least 90% of the matrix by weight is constituted by one or more polymers that do not dissolve in water; 
 ii) the porous matrix has exposed polymer surfaces that are capable of trapping chlorhexidine from an aqueous fluid in which the chlorhexidine is dissolved; and 
 iii) the matrix has a permeability of at least 100 millidarcies relative to water; 
 
 c) disposal of the CX particles and porous matrix in a relative manner to form a microbicidal filter wherein:
 i) the chlorhexidine particles are permanently affixed to the porous matrix; 
 ii) the affixed chlorhexidine particles comprise from 0.5% to 95% of the combined weight of the porous matrix and the chlorhexidine particles affixed thereto; 
 iii) when the fluid is aqueous, release of dissolved chlorhexidine from the microbicidal filter into a flow of aqueous fluid is essentially fully counterbalanced by trapping of dissolved chlorhexidine at the exposed polymer surfaces in the porous matrix, such that when said fluid flow at a rate of 0.3 to 1.3 liter/(minute*square inch) through the microbicidal filter, wherein:
 A) effluent from the filtered fluid flow is free of any detectable taste and odor of chlorhexidine; 
 B) dissolved chlorhexidine, if present in the effluent, is present at less than 3.00 milligrams per liter of effluent; 
 C) each of 2-, 3-, or 4-chloroaniline, if present in the effluent, is present at less than 0.100 milligrams per liter of effluent; and 
 D) such full counterbalancing is sustainable for a throughput volume of at least 800 gallons of water at room temperature per cubic inch of foam in a microbicidal filter; and 
 
 
 d) microbicidal capacity such that, within the sustainable throughput volume at the rate of aqueous flow shown in (c)(iii)(D), the filter kills or otherwise inactivates pathogens from an influent, such that at a minimum the reduction of live cells between influent and effluent occurs to a degree selected from the group consisting of the following:
 i) a 6.6-log reduction in coliform bacteria  Escherichia coli  or  Klebsiella terrigena  for samples having 1×10 7  live cells/100 mL influent; 
 ii) a 4-log reduction in a Coronavirus strain or process resistant viruses poliovirus 1 (LSc) or rotavirus (Wa or SA-11) for samples having 1×10 7  viral particles/L influent; 
 iii) a 3-log reduction in cysts of  Giardia muris  or  Giardia lamblia , for samples having a concentration in the range of 1×10 6  to 1×10 7  organisms/L influent; and 
 iv) a 3.8 log reduction in a  Legionella  bacterial strain for samples having 6×10 3  live cells/L influent. 
 
 
     
     
       2. The system of  claim 1  wherein the water-insoluble polymer(s) is or are selected from the group consisting of: polyurethanes; polyolefins; polyesters; polycarbonates; synthetic and natural polyamides; polyimides; polyacrylates; polymethacrylates; vinyl polymers; rubbers; polyacrylonitrile; polysiloxanes; polysaccharides; and combinations and blends thereof. 
     
     
       3. The system of  claim 1  wherein the water-insoluble polymer(s) has or have a melting transition temperature greater than 57° C. 
     
     
       4. The system of  claim 1  wherein the fluid is selected from the group consisting of: water; ethanol; isopropanol; bodily fluids; medications; air; oxygen gas; nitrogen gas; carbon dioxide; argon gas; nitrous oxide; an anesthetic gas other than nitrous oxide; and mixtures thereof. 
     
     
       5. The system of  claim 1  wherein the influent is an aqueous medium selected from the group consisting of: potable water; a beverage; a stream for transfusion of bodily fluids; an aqueous solution for use in a medical procedure; a recycle stream in a chemical process; a recycle stream in a cell culturing process; and mixtures thereof. 
     
     
       6. The system of  claim 1  wherein the fluid is air that has an average relative humidity selected from the group consisting of at least: 20%; 25%: 30%: 35%: 40%: 45%: 50%: 55%: 60%: 65%: 70%: 75%: 80%; 85%; 90%; 95%; and 100%. 
     
     
       7. The system of  claim 1 , wherein the porous matrix has a form selected from the group consisting of: an open foam; a reticulated foam; a fiber mat; a knitted fabric; a woven fabric; a nonwoven fabric; a material formed by sintering; a material formed by particles attached to one another by a binder; and a monolithic solid in which are defined channels running through said monolithic solid. 
     
     
       8. The system of  claim 1 , wherein the CX solids are affixed to the porous matrix by a means selected from the group consisting of: formation of covalent, ionic, or hydrogen bonds between CX surface molecules and the matrix; the presence of an adhesive between the solid and a matrix surface; adhesion to a matrix surface by a melt step; partial embedding within the matrix; full embedding within the matrix; and physical retention by fibers within the matrix. 
     
     
       9. The system of  claim 1 , wherein the system further comprises a material selected from the group consisting of: an adhesive that affixes CX solids to the matrix; a binder that holds CX solid particles in close proximity to one another; a water-insoluble superabsorbent polymer that retains water in close proximity to the CX solids; and an insoluble hygroscopic salt that absorbs water from fluid media and retains the water in close proximity to the CX solids. 
     
     
       10. The system of  claim 1 , wherein:
 a) the system further comprises grains having a composition selected from the group consisting of: a phosphate of calcium; a carbonate of calcium; carbon; and sand; and 
 b) the grains are disposed before, within pores of, embedded in the porous matrix, or after the porous matrix, relative to a flow of fluid during filtration. 
 
     
     
       11. The system of  claim 1 , wherein the porous matrix is comprised of:
 a) an upstream zone within which the chlorhexidine particles are permanently affixed; and 
 b) a downstream zone that is essentially free of chlorhexidine particles. 
 
     
     
       12. The system of  claim 1 , configured for a method of use that comprises, in order:
 a) supplying an influent fluid for which antimicrobial treatment or assurance of safety is desired; 
 b) physically directing the fluid such that said directed fluid passes through the porous matrix and emerges as effluent; and 
 c) directing effluent from the system for storage, immediate use, or further processing. 
 
     
     
       13. The system of  claim 1 , configured for a device that comprises, in order:
 a) a supply module that provides an influent fluid; 
 b) a treatment module that receives influent from the supply module, and passes said influent through the porous matrix to emerge as effluent; and 
 c) an exit module that receives treated effluent from the treatment module and channels or delivers said treated effluent for storage, immediate use, or further processing; 
 wherein the device further comprises a housing. 
 
     
     
       14. The system of  claim 13 , wherein the supply module, treatment module, and exit module are inline in a continuous purification process. 
     
     
       15. The system of  claim 13 , wherein the system is comprised in a configuration for a batch process in the treatment module. 
     
     
       16. The system of  claim 13 , configured for delivery of purified fluid at the point of use. 
     
     
       17. The system of  claim 13 , wherein the system is comprised in a unit selected from the group consisting of the following: a water treatment facility for multiple end users; a point-of-use filter on plumbing for potable water; a drinking straw; a feature for purification of a fluid during storage of said fluid; a mask for breathing purified air; a filter for a ventilation system; a showerhead; a vaporizer for medical use; a sports mister for cooling; a filter for a fluid supplied to a fermentation broth; a filter for a bodily fluid; and a filter for a medication-containing fluid. 
     
     
       18. The system of  claim 13 , wherein the system is comprised in a treatment cartridge for use in a water supply for a residence, office, production facility, hotel, hospital, cruise ship or water treatment plant. 
     
     
       19. The system of  claim 13 , further comprising a sufficient quantity of a phosphate of calcium to remove at least 50% by weight of a dissolved metal substance from the influent in at least 800 gallons of room-temperature water per cubic inch of foam in a microbicidal filter. 
     
     
       20. The system of  claim 13 , further comprising a sufficient quantity of a purifying substance to remove from the influent at least 50% by weight of at least one inorganic impurity selected from the group consisting of: trivalent arsenic; pentavalent arsenic; hydrogen sulfide; iron; copper; zinc; lead; aluminum; chromium; uranium; or a combination thereof; for at least 800 gallons of room temperature water per cubic inch of foam in a microbicidal filter.